The present invention relates to the preparation of the hydroperoxides of tertiary alkanes, aralkanes and cycloalkanes. More particularly it relates to the autoxidation of tertiary alkanes, aralkanes and cycloalkanes in the presence of selected phosphate compounds. The term autoxidation is understood to mean the reaction of a substance with molecular oxygen without the intervention of a flame. The hydroperoxides of tertiary, aryl and cycloalkanes have been prepared by autoxidation. Generally the results of these preparations have been rather discouraging. Two comprehensive reviews of the prior art of peroxides are "Organic Peroxides, their formation and reactions", E. G. E. Hawkins, D. Van Nostrand Company, Inc., Princeton, N.J. 1961, and "Organic Peroxides", A. G. Davies, Butterworths, London 1961, which are incorporated herein insofar as they describe the prior art.
Most known autoxidation reactions for the tertiary, aryl and cycloalkanes have relatively low selectivities for the hydroperoxides. Generally, product of such oxidations has been a mixture of oxidation products, e.g., the aldehydes, ketones, alcohols, acids, hydroperoxides, water and carbondioxide. If the desired product is a hydroperoxide then the production of such by-products and the necessity of removing some or all of them from the hydroperoxide makes an economically unattractive process. A preferable process would be one that had high selectivity for the hydroperoxide with few and relatively low concentrations of by-products. Such a process would be attractive even if low conversions were necessitated, since the hydrocarbon starting material makes an excellent diluent for the potentially dangerous hydroperoxide. Very often a product such as that described above can be used directly or with a minimum of treatment for the purification and concentration of the hydroperoxide.
It is an object of this invention to provide an improved process for the autoxidation of tertiary alkanes, aralkanes and cycloalkanes to produce hydroperoxides. It is a further object to provide a process which has high selectivity for hydroperoxides. These and other objects will become apparent from the discussion below.